A hearthkeeper's duty is to bring physical and spiritual light and warmth to her congregation. This is accomplished through lighthouses, places of worship of the Bright Way. They evolved out of the open bonfires tended by shamans prior to the Theophany. These bonfires grew into sheltered hearths as the yinrih's society advanced. With the discovery of electricity the hearths evolved into small power plants distributing electricity to the homes of the faithful. These plants burned fossil fuels at first, with a ceremonial hearth located in the sanctuary and the loud and smelly power generation equipment located elsewhere on the property.
As research monasteries continued investigating space, the nature of stars as sustained fusion reactions was eventually discovered. Efforts quickly began to replicate these icons of the Light on a smaller scale for liturgical purposes. Thus was born the fusion reactor, or star hearth. These too were at first located away from the worship space, but as miniaturization proceeded, smaller hearths that resembled stars inside a glass cylinder were able to be incorporated directly into the liturgy.
Between the fossil fuel era and the perfection of the star hearth there was a period where fission reactors were used, with the sanctuary and nave built around a small reactor pool.
Whatever the means of power generation, the hearthkeeper takes the lead role in actively maintaining the equipment and transmission lines. This is why hearthkeepers are both priestess and engineer. Claravian seminaries are centers of theological and pastoral training as well as technical colleges. Helping the hearthkeeper in these tasks are several acolytes. Acolytes can be pups of a certain age, though they must be female. Adult laywomen are also frequently seen as acolytes, and seminarians serve as acolytes as part of their training. Males are permitted to assist in a less technical role as pages--essentially gofers.
The most striking feature of the lighthouse from a human perspective is the presence of bones lining the interior, and occasionally exterior, of the building. A lighthouse is not just a church but also a cemetery. A belief common across yinrih cultures, in and out of the Bright Way, is the idea that to properly honor the dead, one should make good use of their remains. This usually takes the form of using their bones as architectural adornment. The fact that the yinrih are canine and they build things out of bones is a frequent source of comment by humans.
Lighthouses are generally dome-shaped or otherwise incorporate domes into the architecture. This is to mimic the vault of the heavens. Ceilings are painted to resemble the sky, with stars or clouds on a blue background. The bones extend from the base of the wall up a certain height, usually low enough for bonekeepers to easily maintain. Floors may be decorated with natural scenes such as rivers and flora, or in the Outlander tradition of sacred architecture, be painted with icons depicting the lives of saints and martyrs. Support pillars are usually designed to resemble trees as a reminder of the yinrih's arboreal origins. In general, the inside of a lighthouse is meant to resemble Creation in miniature.
The nave of the lighthouse is round. Perches are distributed around the area. The sanctuary is either located in the center of the nave or on the eastern wall. The star hearth is concealed by a shear sanctuary vail outside of liturgies and certain feasts.
Back when lighthouses contained actual hearths, there was an oculus open to the sky that served as a flue for escaping smoke. This became a decorative window after the transition to star hearths. On inner planets where Focus is more prominent, this decorative window takes the form of an arch stretching across the domed ceiling of the worship space. The width and angle of this arch are designed such that the sun always shines into the room as long as it is above the horizon. Take every azimuth and elevation where the sun can appear throughout the day and over the course of the year at that particular location, and connect those points into a solid arc. This represents the size and shape of the window.
Further away from Focus the window is a mere circle above or near the sanctuary. The window is usually stained glass, depicting a yinrih missionary greeting a sophont out of frame.
On orbital colonies, the lack of gravity means that instead of perches, tail bars are used for floating worshippers to anchor themselves in place.